I can't classify source of short circuit another way than . But this time it is made by VAG engineers...
Long story short: Car is Seat Altea XL, MY 2008, 2,0l 16v TDI engine BKD. Fuse was blown. I checked
wiring diagram - there are two parts in engine compartment powered from the same fuse - MAF and crankcase breather heater element. This is first ! Who decided to supply power for important sensor (MAF) from the same fuse as breather heater??? I have seen more than 10 breather heaters with internal short circuit or partial short circuit (overcurrent). But not this time. Heater was clean nice and with current consumption approx 0,8A. But intermittent short circuit exists. Mostly it was not shorted with engine off and reappears some seconds after engine started. Rechecked
wiring diagram - nothing more powered from this fuse. Disassembled almost all wiring in engine compartment - no damages in typical places for Golf5 based cars - loom in front part of engine - nice, loom under battery try - another wire found partially damaged, but not connected with circuits I'm looking for. Next I moved in passenger compartment. Wire from fuse holder disappears in main wiring harness, taller as my hand. It reappears in engine compartment already as 2 wires with different color marking. OK, splicing must be somewhere inside. Physically disassembling main harness looked unreal, I used another methods - connected multimeter beeper between suspected wire and ground and started to shake wiring harness, and it beeped shortly couple of times. Ok, already some results. Checked carefully how and where wiring is fitted and fixed, found that loom is pressed against sharp corner of steering column adjustment mechanism. Removed steering column, opened wiring loom in suspected place and... nothing again! Only outer layers of insulating tape around loom were cut with sharp metal, no damages to wires. So I started to think from another end - I recalled from my own experience, that sometimes in VAG diagrams all components powered from one fuse are not shown in
wiring diagram, if components belong to another system as diagram is titled. So I started to check another diagrams for this car searching for fuse SC15 and made two findings: under "Basic Equipment" another wire from the same fuse was shown - for manual headlight level correction. Quickly checked this circuit - everything ok with it.
So now I'll take a minute off from writing in English and give some time for guessing what else is powered from the same fuse as MAF
(Only original equipment, no aftermarket installations in this car)
